Prevaporizer type combustion chamber having longitudinally movable prevaporizer tube



Oct. 22. 1957 E. H.

PREVAPORIZER TYPE COMBUSTION CHAMBER HAVING FROMM ET AL LONGITUDINALLYMOVABLE; PREVAPORIZER TUBE Filed May a, 1953 3 Sheets-Sheet 1 IN V ENTORS E. flFromm/ w BY 1?. M. Sclzirmer Arro/e/v' Y5 'IIII/I |.l:1IIIIIIIIIIIII1II: rIIIIIIIIIIIIIIIIIII II I II IIIIIIIIII II I I II II4 I4 4 4 4 III 14 1 11411114441 11 1 1 IIIIIIIIIIIIIIIIIIIII IIIIIIIIIII II II I III III III I I I I III I I II II II/ I I I I I III II III II I I IIIIIIIII IIIIIIIIIIIIIIII I IIIII IIIIIIIIIIII IIII II III I I IIIIIIIIIIIIIIII I I I I I I I I I II II I .IIIII I I I I O 22. 1957 E.H. FROMM s-rm. 2,810,260

P E APORI R TYPE COMBUSTION CHAMB HAVING LLY MOVABLE PREVAPORIZ NGITUTUBE 3 Sheets-Sheet 2 Filed May 8, 1953 WW fi INVENTORS E. H Fromzzz/ MY BMJdzirm ATTORN Y6 Oct. 22, 1957 E. H. FROMM ETAL 2,310,260

. PREVAPORIZER TYPE COMBUSTION CHAMBER HAVING LONGITUDINALLY MOVABLEPREVAPORIZER TUBE 3 Sheets-Sheet 3 Filed May 8, 1953 PR-IMARY AIR INLETINVENTORS E. h. FROMM R. M. SCH/RMER I A TTORNEYS United StatesPREVAPORIZER TYPE COMBUSTION CHAMBER HAVING LONGITUDINALLY MOVABLE PRE-VAPORIZER TUBE Ellsworth H. Fromm and Robert M. Schirrner, Bartlesville,kla., assignors to Phillips Petroleum Company, a corporation of DelawareApplication May 8, 1953, Serial No. 353,883

Claims. (Cl. 60-39.71)

This invention relates to prevaporizer type combustion chambers. In afurther aspect this invention relates to a prevaporizer type combustionchamber in a jet engine. In a further aspect this invention relates toprevaporizer type combustion chambers in which the prevaporizer tube islongitudinally movably attached to the closed end of the combustionchamber. In a further aspect this invention relates to a prevaporizertype combustion chamber in which both the prevaporizer tube and theprimary air inlet conduit are longitudinally movably mounted in theclosed end of the combustion chamber.

In aircraft propulsion systems comprising an air compressor, fuel burnermeans at the compressor outlet, a gas turbine driven by the combustionproducts and air heated thereby, said turbine mechanically driving saidcompressor, thrust is developed by reaction arising out of the expansionof the stream of gas through a nozzle 01 jet. One suitable methodutilized in such apparatus is to introduce the fuel into the combustionchamber in the form of a vapor through vaporizer tubes mounted in theupstream end of the tube plate or closed end of said flame tube andextending'into the flame tube. The tube plate forms a closure in theupstream end of the flame tube so that air from the compressor isdirected into the vaporizer tubes, around the flame tube, and throughholes in the flame tube into the combustion zones, and through primaryair ducts locatedin the tube plate which direct air into the combustionzones.

The liquid fuel and vaporizing air are introduced into the upstream endof the vaporizer tubes and the fuel is vaporized in these tubes whichare exposed to the combustion flame. The downstream ends of thevaporizer tubes change direction through approximately 180 and the fueland air mixture formed in these tubes is discharged upstream into thestream of air supplied through an orifice located in the downstream endof the primary air duct located in the closed end. The primary airflowing through the vaporizer tubes assists in the vaporization of thefuel by reducing the temperature required for complete vaporization. Theair also serves to reduce the deposition of carbon on the walls of thetubes, which results from overheating of the fuel, and aids'in thetransport of liquid and vaporized fuel through the vaporizing tubes. Theair entering through the primary, air duct aids in the completion ofcombustion of the vaporized fuel discharged from the vaporizer tubes.

In engines employing tubular type combustion chambers, a number ofvaporizer tubes can be provided in each combustion chamber, these beingarranged symmetrically around a single primary air duct. However, it ismore usual to provide a separate primary air duct for eachvaporizertube. In engines employing an annular type combustion chamber,the same arrangement of vaporizer tubes and primary air ducts can alsobe employed; Each vaporizer tube is an independent source of fuel supplyand a uniform discharge ofvaporized fuel, in accordance with thecombustion requirements ofthe particucombustion in such engines.

lar operating conditions of the engine, must be maintained in order toprovide eflicient and stable combustion in the combustion chamber. Asisevident, various conditions are necessary in order to provide the mosteflicient Regardless of the position of the primary air inlet, it hasbeen found that increased operating efliciency occurs when the outletsof the vaporizer tubes are positioned further downstream as increasedamounts of fuel are burned. Another variable found to be important, isthe flame holding area in the combustion zone, which is varied inaccordance with the inlet air velocity to the combustion chamber. Thisarea may be controlled by regulating the volume of slow moving fuel-airmixture existing between the orifice of the primary air duct and theclosed end of the combustion chamber.

Each of the following objects is obtained by at least one of the aspectsof this invention.

,An object of this invention is to provide an improved prevaporizer typecombustion chamber.. A further object is to provide apparatus forcontrolling the location of the vaporizer tubes in the combustion zoneof a pre vaporizer type combustion chamber in response to at least oneof the components being supplied to said combustion zone. A furtherobject of this invention is to provide apparatus for regulating thevolume of slow moving fuel-air mixture between the air discharge orificeof the primary air duct and the closed end of the prevaporizer typecombustion chamber. A further object of this invention is to provideapparatus so that the most efficient operating conditions will bemaintained at all times.

Other objects and advantages will be apparent to one skilled in the artupon reading this disclosure.

Accompanying this disclosure and a part thereof ar the accompanyingdrawings in which:

Figure 1 is a cross section of a flame tube of a combustion chamber ofour invention;

Figure 2 is a section of a flame tube of a combustion chamber showing amodification of the apparatus of Figure 1; and

Figure 3 is a cross section of further modification of our invention.

Figure 4 is a cross section of a further modification of our invention.

In its broadest aspect, our invention provides apparatus forautomatically controlling the location of the vaporizer tubes in thecombustion zone in accordance with a change in an operating variable inorder to extend the blowout limits, and therefore to extend theoperating range, of the burner configuration. In Figures 1 and 2,apparatus is shown wherein the position of the vaporizer tubes iscontrolled by the air flow, and the fuel respectively, to the vaporizertubes. In Figure 3, the primary airduct is also adjustable.

Two problems are involved in providing stable operati-on where suchapparatus is used. The first of these is mixing a sufficient amount ofthe primary air with the fuel-air mixture flowing from the vaporizertube to give an approximately stoichiometric mixture. This preventsover-richening in the region of the outlet of the vaporizer tube andpossible rich-mixture blow-out, the extent of the mixing being dependentupon the velocity of the primary air and the position of the outlet ofthe vaporizer tube. Thus, as the velocity increases, at a fixed positionof the outlet of the vaporizer tube, less air in the stream mixes withthe fuel-air mixture from the vaporizer tube thereby In this invention,as the 3 divergent airstream with the fuel-air mixture. This tends toprevent overly rich mixtures in the region of the outlet of, thevaporizer tube.

Another consideration is the volume of slow moving air between theclosed end of the flame tube and the downstream end of the primary airduct, which serves as a flame holding zone. As the velocity of primaryair increases, it is desirable to increase this volume. In onemodification of our invention we provide a movable primary air ductwhich results in an increased flame holding zone as the velocityincreases. In this modification it is also desirable to provide amovable vaporizer tube, the movement of this tube being at least asgreat, and preferably greater, than the movement of the primary airduct. The most preferable situation is one in which the movement of theprimary air duct and the vaporizer tube is such that the spatialrelationship of these components increases in an amount equal to thatprovided by the first modification of our invention. It will be apparentto one skilled in the art that the exact amount of movement in either ofthese situations is dependent upon the design of the particularcombustion chamber.

In the attached drawings we have illustrated specific apparatuses forproviding these improved operating conditions. Figure l shows alongitudinal section through a flame tube of a jet engine combustionchamber, the location of the vaporizer tube being controlled through aspring-loaded coupling in accordance with the flow of air to thecombustion chamber. In this figure, a single J-type vaporizer tube isslidably mounted in the closed end 11 of flame tube 12 adjacent to aprimary air duct 13, this primary air duct including primary air tubestructure 14, from which a high velocity, divergent stream of aircontacts and mixes with the vaporized fuel-air mixture from the outletof vaporizer tube 10. Vaporizer tube 10 is slidably mounted through aspring-loaded coupling in closed end 11 by a compression type spring 15located in the annular spacing between the inner surface of cylindricalchamber 16 in the closed end 11 and the outer surface of vaporizer tube10. The action of spring 15 against retaining structure 17 and annularlip 18 on the inlet end of vaporizer, tube 10 is balanced by the impactof the air stream on the surface of lip 18 so that regulation of theextension of vaporizer tube 10 into the combustion zone is proportionalto the air flow from the compressor. Fuel is supplied to the vaporizertube 10 by fuel line 19, this line being rigidly mounted in the inletend of vaporizer tube 10 by support member 20. At the end of tube 13,there is provided orifice plate 30. The secondary air holes 25 in flametube 12 are schematically shown.

In Figure 2, the location of the vaporizer tube is determined by theexpansion of a bellows in the fuel line in accordance with fuel flow tothe vaporizer tube. More specifically, the extension of vaporizer tube10 into the combustion zone is controlled by the degree of expansion ofbellow 21 rigidly attached to the inlet end of vaporizer tube 10 througha section of fuel line 19. Bellows 21 constitutes an integral section offuel line 19 and is located in cylindrical chamber 16 of the closed end11 and downstream from the supporting member 20 to provide a stationarylocation from which bellows 21 can expand and extend vaporizer tube 10into the combustion zone.

through slidable contact with guide 22 rigidly attached to the closedend 11. The inlet end of vaporizer tube 10 is attached to the end offuel line 19 which extends downstream from the bellows, by means ofradial spokes 23 which offer low resistance to the flow of air fromchamber 16 into vaporizer tube 10. An orifice 24 is located in the endof fuel line 19 so that changes in the fuel flowto the combustionchamber through bellows 21 results in a movement of vaporizer tube 10into the combustion zone.

Figure 3 of our invention discloses a modification in which anadjustable primary air duct is provided in the closed end of thecombustion chamber. In the operation of this modification this orificeis extended downstream into the combustion zone by an increase in airvelocity, thus increasing the volume of low velocity air-fuel mix.- tureexisting between the, discharge of this orifice and the closed end ofthe combustion chamber. Conversely this air inlet retracts from thecombustion chamber when the flow of primary air is decreased.

The movement of the primary air duct is preferably accomplished byspring-loading. The primary air conduit 14 is provided with an outer lip32 on the upstream end and an orifice plate 39 on the downstream end andis slidably mounted in the spring retaining chamber 33 in the closed end11 of flame tube 12. Retaining member 35, rigidly attached to the closedend 11, retains compression spring 34 in the spring retaining space 33.Spring 34 maintains the position of the primary air tube 14 through theaction on lip 32 and retaining member 35 in accordance with the impactof the air stream on the surface of plate 30 to regulate the extensionof primary air orifice 14 into the combustion zone and, thereby, thevolume of the region of slow moving air between the closed end 11 of thecombustion chamber and the outlet end of conduit 14.

In Figure 3 the automatic positioning means for vaporizer tube 10 isshown as being similar to the positioning means of Figure l, but it willbe apparent that the vaporizer tube can also be positioned in a mannersimilar to that shown in Figure 2. It will be obvious that the move mentof vaporizer tube 10 could be effected by having a rigid connection 36between tube 14 and tube 10. This would provide an apparatus for movingthese elements further into the combustion chamber while maintainingtheir spatial relationship constant.

In the embodiments shown herein, flame tube 12 is provided withsecondary air holes 25, but primary air holes may also be located nearthe closed end 11 of combustion chamber 12 if desired. I11 the interestsof simplicity the flame tube is shown with only one primary air conduit14 and vaporizer tube 10 but, it will be understood, that our inventionis also applicable in combustion chambers in which a plurality ofvaporizer tubes and primary air tubes are used. Certain additionalelements, such as ignition means, are well known in the art and are notshown.

As many possible embodiments may be made of this invention withoutdeparting from the scope thereof, it is to be understood that all matterherein set forth or shown in the accompanying drawing is to beinterpreted as illustrative and not in a limiting sense.

We claim:

1. A combustion chamber comprising a flame tube having an open end and aclosed end, at least one primary air inlet tube extending through saidclosed end and into said flame tube, at least one prevaporizer tubemounted in and communicating through said closed end, spring retainingmeans attached to said closed end, spring retaining means on the endportion of said prevaporizer tube, a spring between said two springretaining means, and a fuel supply conduit extending into saidprevaporizer tube.

2. A combustion chamber comprising a flame tube having an open end and aclosed end, at least one primary air inlet tube extending through saidclosed end and into said flame tube, at least one longitudinally movablymounted prevaporizer tube mounted in and communieating through saidclosed end, a fuel inlet conduit connected to and communicating withsaid prevaporizer tube, a restricted orifice in the downstream endportion of said fuel inlet conduit, and a bellows section in said fuelinlet conduit.

3. A combustion chamber comprising a flame tube having an open end and aclosed end, longitudinally movable primary air inlet means extendingthrough said closed end and into said flame tube, at least one vaporizertube longitudinally movably connected at its upstream end to andcommunicating through said closed end and extending into 5 said flametube, and means for supplying fuel to said prevaporizer tube.

4. A combustion-chamber comprising a flame tube having an open end and aclosed end, longitudinally movable primary air inlet means extendingthrough said closed end and into said flame tube, said means comprisinga movable air conduit, a spring retaining recess in said closed end, aspring retaining member on the downstream end of said closed end, anorifice at the downstream end of said air conduit, a spring retaininglip on the upstream end of said air conduit, a spring in springretaining recess, at least one vaporizer tube longitudinally movablyconnected at its upstream end to said closed end and extending into saidflame tube, and means for supplying fuel to said prevaporizer tube.

5. A combustion chamber comprising a flame tube having an open end and aclosed end, at least one primary air inlet conduit extending throughsaid closed end and into said flame tube, at least one prevapon'zer tubeconnected at its upstream end to said closed end and extending into saidflame tube, means for supplying fuel to said vaporizing tube, and meansassociated with said prevaporizer tube and responsive to a change inflow of one of the combustion components for longitudinally moving thetube, said last recited means moving the tube downstream in thecombustion chamber in response to an increase in flow of one of thecombustion components and upstream in the combustion chamber in responseto a decrease in flow of one of the combustion components.

References Cited in the file of this patent UNITED STATES PATENTS1,647,409 Klein Nov. 1, 1927 1,815,317 Klein July 21, 1931 2,304,136Woods Dec. 8, 1942 2,522,081 Allen Sept. 12, 1950 2,655,787 Brown Oct.20, 1953

